Power supply is an indispensable device for normal operation of a computer. The power supply has an output connector to couple with a power supply socket of the mainboard. The power supply connectors now on the market generally have two types: one has twenty slots, the other has twenty-four slots. The mainboard socket also has two types: one has twenty slots and the other has twenty-four slots to mate the connectors. In the event that the power supply connector has twenty slots and the mainboard socket has twenty slots, or the power supply connector has twenty-four slots and the mainboard socket has twenty-four slots, the power supply connector can be directly inserted in the mainboard slots. But if the power supply connector has twenty slots while the mainboard socket has twenty-four slots, or the power supply connector has twenty-four slots while the mainboard socket has twenty slots, the power supply connector cannot be inserted in the mainboard slots. In such a situation, a coupling terminal has to be used. Refer to FIG. 1 for a conventional power supply to be coupled with a coupling terminal. The conventional coupling terminal A mainly includes first coupling slots A1, conductive wires A2 and second coupling slots A3. The first coupling slots A1 have twenty or twenty-four slots. The second coupling slots A3 have twenty-four or twenty slots. The first coupling slots A1 and the second coupling slots A3 are connected by the conductive wires A2. When in use, a power supply P has an output connector B inserting in the first coupling slots A1 of the coupling terminal A, and the second coupling slots A3 of the coupling terminal A are coupled with the insertion slots of the mainboard. This is the commonly adopted approach now. As the power supply P and the computer host have to be coupled through the coupling terminal A, and the first coupling slots A1 and the second coupling slots A3 are bridged by the conductive wires A2, the distance between the power supply P and the computer host increases. Hence defects and output voltage drop of the power supply P often occur. Power supply received by the computer host could be not adequate. Moreover, the first coupling slots A1 and the second coupling slots A3 are separated and have to be connected by the conductive wires A2 individually. Molding, material, and fabrication and assembly costs are higher.